This invention relates generally to internal combustion engines, and more specifically, to an improved system for automatically controlling the air/fuel mixture passing to the engine in a manner ensuring proper operation of the engine over a wide spectrum of operating conditions, while simultaneously improving combustion of the volatile mixture and thereby reducing pollutants.
The usual automotive vehicle using a gasoline powered internal combustion engine includes a fuel tank, a fuel pump and a carburetor. The carburetor is provided with a chamber for receiving gasoline from the fuel pump, and a float controlled valve maintains the gasoline at a constant level in the chamber. The usual carburetor includes a venturi through which air for combustion is drawn at substantial velocity, thus producing in the venturi a pressure substantially less than atmospheric. This reduced pressure induces a flow of fuel from the float chamber of the carburetor, and as the gasoline in liquid phase emerges from jets or nozzles within the venturi, it is atomized or vaporized, or both, and mixed with the combustion air flowing through the venturi.
The mixture of air and fuel is delivered to a manifold, and from the manifold is drawn into the engine cylinders during the suction strokes of the pistons therein. The air/fuel mixture is compressed in each cylinder during the compression stroke of the piston, and is then ignited, either by a spark in the conventional engine, or by compression with or without supplementary heating means in a diesel engine. Ideally, combustion of the air/fuel mixture, which is initiated at the spark plug gap, progresses rapidly and is fully complete at the end of the power stroke of the cylinder. Too rapid burning or detonation is wasteful and causes knocking. Too slow burning results in some fuel failing to burn and being discharged in the exhaust. It is recognized that in the usual gasoline engine a very substantial percentage of fuel is wasted, and a relatively small percentage of the total energy available in the fuel is converted into usable energy by the engine.
Due to the inefficiencies of prior engines, many attempts have been made to improve the same by increasing the efficiency of the associated carburetion system. The ultimate purpose in increasing the efficiency of the carburetion system for an engine is to increase the percentage of fuel totally burnt in the cylinders, thereby increasing fuel economy and reducing certain undesirable combustion by-products such as hydrocarbons and carbon monoxide, and increase other more desirable combustion by-products such as carbon dioxide.
It is generally accepted that reduction of harmful emissions could be accomplished by delivering a homogeneous mixture of air and fuel to the engine, thereby allowing lean mixtures to be burned with complete combustion. Known state of the art carburetion-induction devices utilized with the conventional internal combustion engine are capable of providing complete combustion with air/fuel ratios of about 18.5:1. Air to fuel ratios in this range are effective in reducing the undesirable hydrocarbon and carbon monoxide by-products of combustion.
Prior proposed systems for increasing the efficiency of combustion and decreasing the levels of certain undesirable combustion by-products have included apparatus for heating and/or vaporizing fuel prior to injection into the carburetor venturi, devices for preheating air before mixing the same with injected fuel, and various other systems intended to separate the lighter from heavier fuels in a mixture before mixing with air. Although many different systems have been proposed for increasing the efficiency of internal combustion engines and reducing pollutants, none have proved entirely satisfactory over the broad spectrum of engine operating conditions, as those commonly encountered in automobile engines.
In this regard, it has been found that it is not only necessary for a system to be susceptable to tight control of the air/fuel ratio, but the system must also have the flexibility to allow change in the air/fuel ratio which changes with varying load conditions. If the system does not have this flexibility but does have the ability to maintain a constant air/fuel ratio, it would only really be effective over a desired or given operating range and would not function well outside such range.
Accordingly, there has been a need for an improved internal combustion engine pollutant control system which is capable of tightly controlling the air/fuel mixture ratio received into the intake manifold, which system also has the flexibility to allow a change in the air/fuel ratio with changes in engine load conditions and speed. In particular, there is a need for an improved system which is capable of maximizing fuel efficiency in automobile engines, while simultaneously permitting changes in the air/fuel mixture to ensure engine responsiveness to typical driving conditions. Such a system should preferably be adapted for use with existing carburetion systems, be capable of use with such existing carburetion systems while also requiring minimal modification to the same, and be constructed of components known to be able to withstand the rigors of long term automobile engine usage. Additionally, in connection with the foregoing, there is a need for a novel apparatus capable of safely and efficiently heating and partially vaporizing fuel into a specific mixture, and associated apparatus for controlling passage of the heated and partially vaporized fuel mixture to the carburetor. Such systems and apparatus should be of simplified construction, and maximize use of existing engine components. The present invention fulfills these needs and provides other related advantages.